LXR linux/include/linux/rcutiny.h

   1/*
   2 * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License as published by
   6 * the Free Software Foundation; either version 2 of the License, or
   7 * (at your option) any later version.
   8 *
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, you can access it online at
  16 * http://www.gnu.org/licenses/gpl-2.0.html.
  17 *
  18 * Copyright IBM Corporation, 2008
  19 *
  20 * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
  21 *
  22 * For detailed explanation of Read-Copy Update mechanism see -
  23 *              Documentation/RCU
  24 */
  25#ifndef __LINUX_TINY_H
  26#define __LINUX_TINY_H
  27
  28#include <linux/ktime.h>
  29
  30struct rcu_dynticks;
  31static inline int rcu_dynticks_snap(struct rcu_dynticks *rdtp)
  32{
  33        return 0;
  34}
  35
  36/* Never flag non-existent other CPUs! */
  37static inline bool rcu_eqs_special_set(int cpu) { return false; }
  38
  39static inline unsigned long get_state_synchronize_rcu(void)
  40{
  41        return 0;
  42}
  43
  44static inline void cond_synchronize_rcu(unsigned long oldstate)
  45{
  46        might_sleep();
  47}
  48
  49static inline unsigned long get_state_synchronize_sched(void)
  50{
  51        return 0;
  52}
  53
  54static inline void cond_synchronize_sched(unsigned long oldstate)
  55{
  56        might_sleep();
  57}
  58
  59extern void rcu_barrier_bh(void);
  60extern void rcu_barrier_sched(void);
  61
  62static inline void synchronize_rcu_expedited(void)
  63{
  64        synchronize_sched();    /* Only one CPU, so pretty fast anyway!!! */
  65}
  66
  67static inline void rcu_barrier(void)
  68{
  69        rcu_barrier_sched();  /* Only one CPU, so only one list of callbacks! */
  70}
  71
  72static inline void synchronize_rcu_bh(void)
  73{
  74        synchronize_sched();
  75}
  76
  77static inline void synchronize_rcu_bh_expedited(void)
  78{
  79        synchronize_sched();
  80}
  81
  82static inline void synchronize_sched_expedited(void)
  83{
  84        synchronize_sched();
  85}
  86
  87static inline void kfree_call_rcu(struct rcu_head *head,
  88                                  rcu_callback_t func)
  89{
  90        call_rcu(head, func);
  91}
  92
  93#define rcu_note_context_switch(preempt) \
  94        do { \
  95                rcu_sched_qs(); \
  96                rcu_note_voluntary_context_switch_lite(current); \
  97        } while (0)
  98
  99static inline int rcu_needs_cpu(u64 basemono, u64 *nextevt)
 100{
 101        *nextevt = KTIME_MAX;
 102        return 0;
 103}
 104
 105/*
 106 * Take advantage of the fact that there is only one CPU, which
 107 * allows us to ignore virtualization-based context switches.
 108 */
 109static inline void rcu_virt_note_context_switch(int cpu) { }
 110static inline void rcu_cpu_stall_reset(void) { }
 111static inline void rcu_idle_enter(void) { }
 112static inline void rcu_idle_exit(void) { }
 113static inline void rcu_irq_enter(void) { }
 114static inline bool rcu_irq_enter_disabled(void) { return false; }
 115static inline void rcu_irq_exit_irqson(void) { }
 116static inline void rcu_irq_enter_irqson(void) { }
 117static inline void rcu_irq_exit(void) { }
 118static inline void exit_rcu(void) { }
 119#ifdef CONFIG_SRCU
 120void rcu_scheduler_starting(void);
 121#else /* #ifndef CONFIG_SRCU */
 122static inline void rcu_scheduler_starting(void) { }
 123#endif /* #else #ifndef CONFIG_SRCU */
 124static inline void rcu_end_inkernel_boot(void) { }
 125static inline bool rcu_is_watching(void) { return true; }
 126
 127/* Avoid RCU read-side critical sections leaking across. */
 128static inline void rcu_all_qs(void) { barrier(); }
 129
 130/* RCUtree hotplug events */
 131#define rcutree_prepare_cpu      NULL
 132#define rcutree_online_cpu       NULL
 133#define rcutree_offline_cpu      NULL
 134#define rcutree_dead_cpu         NULL
 135#define rcutree_dying_cpu        NULL
 136
 137#endif /* __LINUX_RCUTINY_H */
 138